Arent Jansz (Jans), born 28 May 1610 at Groningen, died there 6 October 1679, was a Dutch Mennonite elder of the Groningen Old Flemish Mennonites, serving in his home town from about 1636 until his death. He was a rather wealthy merchant and in 1636 was one of the founders of the Groningen Old Flemish congregation, then usually called Arent Jansgemeente. In 1677 he bought a plot behind his house "de Block" in the Boteringestraat, on which a meetinghouse was built for the congregation, which still stood in the mid-20th century (rebuilt in 1813-1815); in 1678 he contributed liberally for this building. In 1664 at his expense a new edition of <em>Veelderhande Liedekens</em> was printed by I. van Wesbusch at Haarlem. This was used as a hymnbook in the Arent Jans congregation. Arent was married to Albertje Jans Mabe; he was a son of Jan Arents in't Block, and a grandson of Arent Cornelis, a Catholic priest who had left the Catholic Church about 1580 to join the Mennonites. Both Arent Jansz's father Jan Arents and his father-in-law Jan Jansz Mabe of Groningen were preachers or deacons in the Flemish congregation, and had attended the debate held at Middelstum in 1628 on the question whether the Flemish congregation should unite with the other Mennonites. Arent Jansz's daughter, Albertje Arends Blok, was married to Willem Hesselink (1648-1720), a preacher of the Groningen Old Flemish Mennonites at Enkhuizen and later at Groningen.